Hey,
This is kind of a very basic question for a debate I'm having with a fellow optician. He is trying to convince me taking an OC for single vision lenses is not important. I know that if the prism is the same in both eyes it's supposed to be fine. However I've always used the OC to help with better vision.
Am I in a minority fir taking the OC?
Now granted he also skips the OC for digital lenses.
Originally Posted by Boldt
Digital and Aspheric should always have pupil heighttaken into consideration, and a pupil height should ALWAYS be taken IMO, maybe not always used to offset the OC in edging, but should be information used in making this decision.
Many times moving the OC of the lens right in front of the pupil is silly and will lead to issues in edging, frame fit/look, but it should be an integral part of that decision.
Now if we are talking -50 OU or +1 readers then maybe one could skip the whole excerise
Digital lenses you have to put the OC in front of the eye or they aren't working right, probably worse than if you had not used a digital SV design. Use Martin's Tilt Rule (- 1mm OC below Pupil height for each degree of Pantoscopic angle) for offseting the OC in aspheric lenses, Digital lenses just put the pupil height as the OC.
These are necessary things to do.
At what power do you start to sell "digital" and asheric's?
I fail to understand why this is so hard for so many dispensers to do. We take an OC every time. And with frame size once again on the increase, it seems more applicable now than perhaps in decades past. I would suggest you're far more likely to run into visual "issues" from induced yoked prism induced by sloppy dispensing practices, than with the use of say, the dreaded devil lens poly.
I suppose not taking measurements which will add maybe a minute at most to the dispensing time is okay, if you like doing a half assed job. Personally, I like to have as much information as possible. Perhaps inducing .5 prism dioptres might not be a big deal (although you do find some exceedingly sensitive patients sometimes), but what do you gain in not even checking?
You may well be in a minority, but that minority are doing their job as dispensers properly.
Playing devils advocate here---
A -.50 rx needs to be decentered how much to induce .5D yoked vertical prism?
So it's not worth getting them exactly where they should be? I know what you're saying, but I just don't see the reasoning.
I also feel like these kind of measurements make us looking more professional. If my tailor (I don't have a tailor) didn't take many measurements, I would not think he was as good as someone who took more. And I suppose that's because I don't know about making suits. I think the same can apply to our patients.
This. +1.I fail to understand why this is so hard for so many dispensers to do. We take an OC every time. And with frame size once again on the increase, it seems more applicable now than perhaps in decades past. I would suggest you're far more likely to run into visual "issues" from induced yoked prism induced by sloppy dispensing practices, than with the use of say, the dreaded devil lens poly.
So back to the original question- Do you ALWAYS (OP's caps) need to take OC heights?
Unless you think off the rack (branded=digital*) cloths should always be tailored the answer is no and Boldt loses the bet.
I further think the question should've been qualified with a specific < power.
*Also who's "digital" lenses are we talking about?
(Boldt- please put me in touch with the winner so I can get a cut!)
[Post #1 seems to have been edited so ALWAYS and aspheric no longer appear]
Last edited by Uncle Fester; 07-18-2014 at 01:38 PM. Reason: tweak...
You loose nothing in taking the extra - what - 10 seconds??? to dot a proper OC for every patient, every time.
In fact, you gain both a more accurate finished product 100% of the time, more relevance and respect for a job properly done in the patients mind, decreased likelihood of a pt returning with "phantom" nondescript acuity or eyestrain complaints, and the added bonus of becoming better at your progressive fitting for no extra cost! Win, win, win, and win again!
If your office is simply too busy to be bothered to take an OC for every patient, every time, regardless of SRx, or worse you feel it's just unimportant for any reason - might I suggest a career in an online glasses dispensing biz from your garage?
Didn't we just have a long discussion over OC height for function as well as cosmetics?
I believe Daryl M. chimed in that 3mm below pupil was acceptable and was supported by Robert M.
Wish my search skills were better.
Uncle Fester: I like to sell the to people with a cyl or -1 or more or a Shpere of +2/-2. I could see the difference at a -.75 cyl and now at a -1.25 cyl I tried stock and never again. Honestly with Digitals I think they are for every one, price is a factor I know, but the quality you get is worth it.
:^) I'll let him know that you want in. Though with the responses I'm seeing I may have won here.
I love it!
FWIW I am a -5.50 -1.00 cyl
-5.75 -0.75 cyl
and I like SemiFinished Aspheric 1.67 or 1.70 better than any digital I've had, plus they come out MUCH thinner than Surfaced, which I care about as well ;)
For those that are taking OCs, if you are putting the OC at Pupil height, and most frames are set with 9degrees Panto to begin with, aren't you then edging the lenses with OCs 2 to 3 mm functionally above where The patient is looking out of?
Isn't why we add Panto to progressives to help the patient "get to the reading" faster because it artificially raises the OC in the lens by changing the angle it is being viewed out of?
Always measure Pupil heights. Do NOT always change the OC.
Tallboy,
Is the OC height different that then pupil height?
What lab are you using? I can get a script like yours in poly as thin as 1.67 stock. You have to tell them what your looking for. And what kind of digital? I'm just wondering not trying to contradict you by any means I'm Just curious. :^)
As for the panto for sv if we mark where the pupil sits wouldn't this account for any tilt?
Please PLEASE PLEASE!
You're NOT taking "OC" heights any longer
YOU ARE TAKING PUPIL HEIGHTS!
PLEASE!!!!
B
lol Well when you put it that way, no prob. :^)
Oh my... bold print AND caps! Point made!
Semantics perhaps - but no wholesale lab I've ever worked with called this measurement anything but OC. In the end, we need to know how to take this measurement consistently (on pre-adjusted frames), and the strength of the SRx (as it relates to this measure) truly should be the least of our concerns.
In the immortal words of the Stay Puft marshmallow man - Just Do It!
When I am edging a semifinished lens I take into account where the patients pupil sits in the frame when I choose where I am going to put the optical center of the lens. When I am ordering surfaced lenses I order where the OC will be when I am going to edge the lens, that may or may not be where the pupil height is (especially if there is going to be an oversized lens charge.)
As far as digitally designed yes I order and edge them perfect OC in front of eye every time, otherwise what is the point of even doing them?
As far as the lenses I have worn it was the Zeiss Individual 2 sv, Auto II SV, and some IOT SV, and a Unity SVX SV, they are all good, some afforded a bit more clarity in peripheral vision for me, but none of them wowed me over a Seiko Aspheric or even a Somo Aspheric 1.67, or Vision Ease 1.70 Aspheric (which I LOVE).
Those Aspheric lenses all have incredibly flat base curves and a 1.0 mm center thickness in 1.67/1.70. All the digital lenses I have gotten are closer to 1.5mm, and not nearly as thin. If the optics were WOW, then maybe I would want the extra thickness.
I mostly use digital lenses for people when I think it will benefit, or if it is a wrap type frame, otherwise I rarely use POW for SV. Maybe I'm making bad decisions but its been working for my patients and I get no complaints. I don't always use aspherics mind you, the flat lenses are terrible in some frames but I use them when possible, unless digital surfaced/design lenses are called for to help with base curve differences (like a frame with 8 base lens)
I use POW on about 40% progressives I dispense
For clarification; OC (Optical Center) is that point of the lens where light passing thru does so without deviation. You don't take OC's as they are in every prescription lens. You can take vertical measurements to place the OC at the patients pupil. Whether you want to call it a pupil height measurement or an OC height measurement for vertical decentration (pupil height seems to be more accurate in its terminology) but we don't take OC's.
,
Not just 'pupil heights' though, is it? It's more like 'pupil point'. Which is a term I might just well start using, provided I don't fall victim of the emboldened, chastising typography as seen above...
So with digital SV lenses you don't drop the OC based on the panto?
I would have thought that would depend on the design - don't some labs required the panto, and compensate for you? Otherwise, I can't understand why you wouldn't compensate, what with angle of gaze yada yada yada
It drops by itself. That's why they cost more. :)
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